Ben MK3 calipers are the same fitment as MK4, so on your car you would still have to flip MK3 calipers upside down
Post-88 MK2, MK3 and MK4 have the handbrake cable on the bottom, pre-88 MK2 and scirocco 16v have the handbrake cable on the top. Hence the need to install the later calipers upside down on a pre-88. Post 88 MK2s MK3 and MK4 calipers bolt right on the same way, though different hoses on MK4
Later MK3 & MK4 use the same design of handbrake mech so are less prone to seizing, however MK4s are more prone to the bleed nipple seizing in due to corrosion between the different metals, theres a name for this but I can never remember it. MK4s are lighter, and they do apparently have better handbrake force, I assume due to an improvement on the mechanism inside the piston? The piston size is the same between late mk2, mk3 and mk4. The early MK2 has a smaller piston.
The only real advantage to the MK4s is the weight, MK2/3 are more than strong enough for a MK2. But you have to factor in the extra cost of the conversion hoses when fitting them, so unless you get the calipers dirt cheap I'd go with the MK3s.
Worth noting that some of the very early MK3s came with MK2 calipers on, the way to tell is to check for the big spring on the outside. if there is one its a MK2 type, if not its MK3.
